We have recently discovered a method to increase the absorption into draining lymph nodes of materials injected into the peritoneal cavity of rats. Applying this method to the study of experimental allergic encephalomyelitis (EAE) has enabled us to produce four new variants of this autoimmune disease: spastic, superacute, chronic demyelinating, and relapsing. Our aim is to establish the basic experimental requirements for uniform production of each of the new variants. The various patterns of localization of superacute EAE in the CNS will be studied, and an attempt will be made to control the distribution observed. The natural history of the chronic demyelinating and relapsing variants must be determined, and evidence of remyelination sought. In each instance, the putative relation between excessive absorption of antigenic inoculum and the clinical and pathologic peculiarities of the new EAE variants will be examined critically. These new procedures also offer unique opportunities to study the roles, if any, of CNS antigens other than myelin basic protein in chronicity, as well as the role of the antigenic depot in chronicity and relapses. Spasticity, chronicity, demyelination and relapses are important aspects of multiple sclerosis. Hyperacute or superacute syndromes occur in demyelinating diseases related to multiple sclerosis. Therefore, the results of this research should be highly relevant to multiple sclerosis. The availability of new forms of EAE and a better understanding of the mechanisms of their development should improve the utility of EAE as a model for multiple sclerosis, with respect to both pathogenesis and evaluation of proposed treatments.